Help with Time Period Query

Question

Dear Forum,
I am trying to put together a SQL such that it lists my Invoices in aging bucket depending upon when I run the report
For eg :
inv number , 0-1 , 1-2, 2-3 , 3-4 and so on months.
For given report run date and invoice date , it should put the inv in correct aging column
a) rpt run dt = 06-Jan-11
inv dt = 13-Dec-2010
aging column = 1-2 months
b) rpt run dt = 06-Jan-11
inv dt = 03-Jan-2011
aging column = 0-1 months
c) rpt run dt = 14-Feb-11
inv dt = 13-Dec-2010
aging column = 2-3 months
d) rpt run dt = 06-Feb-11
inv dt = 01-Feb-2011
aging column = 0-1 months
Basically, if the inv date is in same month as report run dt then its aging column - 0-1
Inv date beyond this is 1-2, 2-3 and so on.
I tried below but it doesn't work for case a) , b) ...
select invnum,inv_amt,
case
   when to_number(to_char(sysdate,'MM'))-to_number(to_char(invdate,'MM'))<1 then
    inv_amt
else
   0
end col_0_1,
case
when to_number(to_char(sysdate,'MM'))-to_number(to_char(invdate,'MM'))>=1 and to_number(to_char(sysdate,'MM'))-to_number(to_char(invdate,'MM'))<2
            then
   inv_amt
else
  0
end col_1_2
------ ..... and so on .
from
invoices_tab;Your help would be appreciated.
Thanks
Shankar

Answer 1

Hi,
As Maxim said, you can do that with built-in functions. For example:
SELECT     CASE
            WHEN  inv_dt >                      SYSDATE                     THEN 'Future'
         WHEN  inv_dt >=              TRUNC (SYSDATE, 'MONTH')       THEN  '0-1 Months'
         WHEN  inv_dt >= ADD_MONTHS ( TRUNC (SYSDATE, 'MONTH'), -1)  THEN  '1-2 Months'
         WHEN  inv_dt >= ADD_MONTHS ( TRUNC (SYSDATE, 'MONTH'), -6)  THEN  '2-6 Months'
                                                                          ELSE  'Over 6 Months'
     END     AS aging_bucket
,     ...If you're doing the exact same thing in several different statements, then you might want to write your own PL/SQL function. That will certainly be more convenient, but it will be slower than doing the whole job in SQL.